The Genesis is a fourth-generation video game console released by Sega in Japan in 1988 and Europe in 1990. The console was released in North America in 1989 under the name Genesis, as Sega was unable to secure legal rights to the Mega Drive name in that region. The Mega Drive, heavily marketed as "16-bit" due to its hardware, was Sega's fifth home console and the successor to the Sega Master System, with which it is electronically compatible.

The Mega Drive was the first of its generation to achieve notable market share in Europe and North America. It was a direct competitor of the TurboGrafx-16 (which was released one year earlier in Japan under the name PC Engine, but at about the same time as the Genesis in North America) and the Super Nintendo Entertainment System (which was released two years later). The Mega Drive began production in Japan in 1988 and ended with the last new licensed game being released in 2002 in Brazil.

The Mega Drive was Sega's most successful console, with over 29 million units sold worldwide. The console and many of its games are still popular today: Some games have been re-released in compilations for newer consoles and/or offered for download on various online services, such as Xbox Live Arcade and Virtual Console. The console is also still popular for fan translations and indie game development.